OPERATIONS: SAFETY
FAA orders disc
checks on CF6-6
Compulsory checks have been ordered on certain General
Electric CF6-6-series engine fan
discs on McDonnell Douglas
DC-10-lOs. On October 7 the US
Federal Aviation Administration
(FAA) airworthiness directive
(AD) becomes effective requiring
ultrasonic inspection of a defined
group of discs in addition to
those already undergoing
inspection following the Sioux
City DC-10 accident in July. Five
operators are affected by the
move.
The AD is unusual, taking the
form of a "final rule" but allowing
a 30-day period for comment
because the work demanded
(and possible aircraft downtime)
could be considerable. "The AD
is needed to identify and remove
from service Stage 1 fan discs
which may have metallurgical
imperfections [which] can
adversely affect the service life of
the disc," says the Federal Avi
ation Administration.
Following the Sioux City acci
dent, airlines were required to
check for metallurgical imper
fections in "all companion disc
forgings from the same melt lot".
This was done, even though the
Sioux City disc fragments have
not yet been found to establish
for certain that a metallurgical
flaw had anything to do with the
break-up.
General Electric says that
fewer than 100 of the discs
affected by the new AD are still in
service. The affected airlines are
United, American, Continental,
Federal Express, and Turkish
Airlines.
The new directive states: "A
further review of process records
has revealed three populations of
material heat lots having differ
ent susceptibility to [metal
lurgical] imperfections. Although
the relationship of these material
imperfections to the material
imperfections of the fracture of
the disc involved in the Sioux
City accident has not been estab
lished, the FAA has determined
that ultrasonic inspections are
required to ensure that detri
mental imperfections are not
present."
The inspections involve disc
removal and immersion in fluid
during the lengthy ultrasonic
test. As FAA tests continue, the
AD says, the instructions may be
modified. The FAA also says "...
a good case exists for making this
amendment effective in less than
30 days," yet it has shied away
from actually doing it. Q
USAir's 737-400 lies in East Bay after its aborted La Guardia take-off
Still no answer to USAir crash
Pilot error, mechanical prob lems, and poor runway condi
tions are being cited as possible
contributors to the USAir
737-400 crash at New York's La
Guardia Airport last week.
Two passengers were killed
when the aircraft, destined for
Charlotte, North Carolina, slid
into the East River after the pilot
aborted take-off last Wednesday
night. The 7,000ft runway was
wet, and light rain was falling.
Rescue teams quickly pulled
the 61 survivors out of the river.
Many were clinging to driftwood,
or to parts of the aircraft. The
737, which had been in service
with the airline just nine months,
was broken into three parts, the
nose section impaling itself on a
wood and concrete pier that
supports a set of runway lights.
UTA DC-10 "mid-air explosion" investigated
AFrench investigation team has joined an international
enquiry commission looking into
the crash of a Union de Trans
ports Aeriens (UTA) McDonnell
Douglas DC-10 destroyed in a
mid-air explosion thought to
have been caused by a bomb.
The two black boxes were
recovered late last week and
taken to Paris, where early exam
ination showed that everything
was normal before the crash.
Debris examined by the French
authorities is said to show traces
of explosive. Inquiries are now
being directed towards a
Lebanese Shi'ite group being
responsible.
The September 19 explosion
over the Sahara Desert killed all
156 passengers and a crew of 15.
The aircraft was on a flight from
Brazzaville to Paris with a stop
over at N'Djamena, Chad.
Debris was scattered over a
100km2 area in the Tenere desert
in Niger territory.
The aircraft, purchased by
UTA in 1973 with US registration
N54629, had logged 60,267 fly
ing hours in 14,777 flights.
The DC-10, Flight 772, took
off from N'Djamena Airport in
Chad at 1213h, and Capt Geor
ges Raveneau made his last VHF
radio contact with the control
tower at 1234h during the ascent
to 8,000m indicated. Everything
was normal, then there was abso
lute silence.
The French inquiry team
includes experts from the
Defence Ministry, Interior Minis
try, Transport Ministry, Office of
air accidents and the flight con
trol office.
Among the passengers on
board were Bonnie Pugh, the
wife of US Ambassador to
Chad Robert L. Pugh, Chadian
Planning Minister Soumaila
Mahamat, four British nationals
working for the Esso oil com
pany, 50 French citizens, and
100 Africans. The crew members
were all French.
In 1984 a UTA DC-8 was dam
aged in an explosion at
N'Djamena Airport. •
National Transportation Safety
Board investigator James Kolstad
says that the cockpit voice
recorder registered "... no sound
or voices that indicate there was
any problem with the take-off, or
why the take-off was aborted".
The flight date recorder shows
minor rudder deviations during
the take-off roll, however, consis
tent with skid marks sub
sequently found about halfway
down the runway.
Both the captain and the
copilot of the flight have been
suspended. It was the copilot's
first operational flight in a Boeing
737, and the pilot had just 138h
captaining the type. Several
apparent irregularities in their
performance before and during
the take-off are being
investigated. •
Bond Helicopters W
e have been asked to
clarify a report in Flight
for September 23 concerning
the ditching of a Bond Helicop
ters MBB BO.105. In a refer
ence to fuel system booster
pumps we quoted. the UK
DoT Air Accidents Investigation
Branch (AAIB) as saying: "All
pumps had severe corrosion on
their motors and damage to
capacitors as a result of salt
water intrusion into the motor
case." This did not necessarily
imply that the pumps were cor
roded before the crash. The
AAIB has since concluded that
the most likely cause of the
ditching was a double engine
flameout caused by ice, slush,
or snow ingestion.
10 FLIGHT INTERNATIONAL 30 September 1989